The Knard is of a slightly different ilk. The one you are currently viewing is 3" wide and designed for an extra wide 29" (622mm ETRTO) rim. This is not just a 29er tire though, it's 29+, so dubbed by Surly to illustrate that it offers you more than just more cushion for the pushin'. 29+ offers a lot. The larger diameter smooths uneven ground, the increased volume adds a bit of 'suspension', the width increases traction, and the sheer size holds speed well. Singletrack beware. Bushes, prepare to be whacked.